While details of RIL's appeal before the Securities Appellate Tribunal (SAT) could not be immediately obtained, Sebi has previously issued show-cause notices to the company in cases involving sale of shares of its erstwhile subsidiary Reliance Petroleum Ltd (RPL) and allotment of shares to certain firms against warrants linked to privately placed debentures issued by RIL.

In the case involving sale of shares of RPL, Sebi is said to have been investigating for a long time the alleged violation of insider trading regulations by RIL.

RPL used to be a separately-listed company, but it was later acquired by RIL and the merger process was also completed way back in 2009.

RIL has previously sought to settle the case through Sebi's consent mechanism, which allows for settlement of cases without admission or denial of guilt after payment of certain charges and disgorgement of ill-gotten gains, if any.

However, Sebi has rejected RIL's consent pleas on more than one occasion, terming the proposed payments as too less and on other grounds.

As per the company's annual report for the fiscal year 2011-12, Sebi had issued it show-cause notices in connection with the sale of shares of erstwhile RPL and the allotment of RIL shares to certain companies against detachable warrants attached to privately placed debentures issued by it.

"The company has submitted its reply to the same," RIL had said in the annual report.

RIL is currently buying back shares under a programme launched in February last year and has repurchased shares over Rs 3,800 crore from public shareholders since then -- achieving 37 per cent of the targetted amount of Rs 10,440 crore.

The buyback programme, already the biggest buy-back by an Indian company, would end on January 19, 2013.

Yesterday, Sebi proposed significant changes to existing framework for buyback of shares by companies from open market, including lowering the process for its completion to three months and a minimum repurchase of 50 per cent of the target.

The proposals have been made in a discussion paper floated by the market regulator and a final decision would taken after taking into account comments from the public.